Index: include/llvm/IR/GlobalVariable.h
===================================================================
--- include/llvm/IR/GlobalVariable.h
+++ include/llvm/IR/GlobalVariable.h
@@ -105,18 +105,13 @@
   /// hasUniqueInitializer - Whether the global variable has an initializer, and
   /// any changes made to the initializer will turn up in the final executable.
   inline bool hasUniqueInitializer() const {
-    return hasInitializer() &&
-      // It's not safe to modify initializers of global variables with weak
-      // linkage, because the linker might choose to discard the initializer and
-      // use the initializer from another instance of the global variable
-      // instead. It is wrong to modify the initializer of a global variable
-      // with *_odr linkage because then different instances of the global may
-      // have different initializers, breaking the One Definition Rule.
-      !isWeakForLinker() &&
-      // It is not safe to modify initializers of global variables with the
-      // external_initializer marker since the value may be changed at runtime
-      // before C++ initializers are evaluated.
-      !isExternallyInitialized();
+    return
+        // We need to be sure this is the definition that will actually be used
+        isStrongDefinitionForLinker() &&
+        // It is not safe to modify initializers of global variables with the
+        // external_initializer marker since the value may be changed at runtime
+        // before C++ initializers are evaluated.
+        !isExternallyInitialized();
   }
 
   /// getInitializer - Return the initializer for this global variable.  It is
Index: test/Transforms/GlobalOpt/available_externally_global_ctors.ll
===================================================================
--- /dev/null
+++ test/Transforms/GlobalOpt/available_externally_global_ctors.ll
@@ -0,0 +1,22 @@
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.11.0"
+
+; RUN: opt -S -globalopt < %s | FileCheck %s
+
+; Verify that the initialization of the available_externally global is not eliminated
+; CHECK: @llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @foo_static_init, i8* null }]
+
+@llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @foo_static_init, i8* null }]
+@foo_external = available_externally global void ()* null
+
+define internal void @foo_static_init() {
+entry:
+  store void ()* @foo_impl, void ()** @foo_external
+  ret void
+}
+
+define internal void @foo_impl() {
+entry:
+  ret void
+}
+